<!doctype>
<html>
	<head>

	</head>
	<body>

	<div id="xx"></div>

		
		
		<script>
var a = 1;

let f = () => {a+=1; alert(a); alert(this)};

setTimeout(() => {alert(this.a);alert(a)},1000)


var x = function(){
	setTimeout(() => {alert(this.a);alert(a)},1000)
}

x.call({a:3,b:2});
		</script>			
	</body>
</html>